X-ray films are widely used for non-destructive testing of materials and for medical diagnosis. In addition to the x-ray image, it is frequently necessary to provide a film with data specific to the image. Examples of such data are the date of exposure, the name of the technician, the type of film, the tube voltage and a description of the x-rayed object. For medical purposes, data relating to the patient are also required, e.g., name, birth date and insurance. Currently, patient data are listed on a printed or typewritten card which is prepared for the patient and imaged onto the film. However, since the data are often fed into a central processor where they are available in digital form, it would be desirable to print the data directly on the film.
Frequently, the patient data are fed into the central processor by means of a terminal (a keyboard or PC) or are read into the central processor from a patient data card (C2 card) via a magnetic card reader or bar code reader. The digitized data can then be centrally processed in a patient data system and transferred to other apparatus.
A system for printing data on x-ray film is known from the International publication WO 89/06377. In this system, patient data are printed directly on an x-ray film by means of LEDs in an x-ray photography unit. The film is accommodated in an x-ray film cassette having an exposure window through which the patient data are printed on the film. The LEDs, which are arranged in a row, are moved past the exposure window in a direction transverse to the row. The data are printed on the film in the form of alphanumeric symbols by activating the individual LEDs sequentially or simultaneously. Each symbol is here constituted by a multiplicity of printed data points.
The system disclosed in the International publication WO 89/06377 is suitable for mammographic film. However, it cannot be employed for all types of film and all applications.